Question about patients calling for help.

I recently started a non-clinical job in a hospital while I am thinking about going back to school to pursue a career in the healthcare field.
This opportunity has provided valuable insight into the environment that I want to work in. I have one troubling question: Why are calls for help ignored on a regular basis? I understand patient ratio is overwhelming, but it is really sad. There was one patient that you could hear pain in their voice, calling for help and when I told a nurse about it was dismissed as “dementia”, which seems to be code word for, "I’m too busy to be bothered with that patient again." If cognitive function and/or psychological issues seem to be so prevalent with patients why are nurses and staff not properly trained to deal with such issues? Ignoring is not dealing –IMO. It is tremendously disruptive and disturbing to other patients and family members/visitors to witness and hear this carrying on while the hospital appears to take an unfeeling and from all appearances, neglectful stance by not doing anything. Was it not in the news recently about a hospital ER getting in trouble for ignoring a patient’s cry for help and then the patient dying. Why is this allowed to go on? This is not how I would want my family member to be treated. Please help me understand, because I’m starting to feel that I may not be callus enough to work in the medical profession.